1. Field of the Invention
The field of the invention disclosed herein is directed to signal processing and more specifically to optimal signal acquisition and especially pertaining to automatic control of real-time sensing systems.
2. DESCRIPTION OF RELATED PRIOR ART
The prior art offers several definitions and methods of "optimal" signal acquisition and associated automatic sensor gain control. For analog signal reception or recording, the popularly accepted approach has been to roughly maximize the received signal power while avoiding saturation. This technique is typically performed either by a human operator or built-in AGC (automatic gain control) circuit defined below. In the case of digital signal acquisition (quantization) the conventional approach is known as "minimum mean-square-error" quantization first formally documented by Joel Max in his 1961 paper "Quantizing for Minimum Distortion". In this approach, a human operator or AGC circuit controls an analog signal level while a uniform n-bit level digitizer quantizes the signal into discrete samples.
There are significant problems with the prior art that preclude extraction of the optimal amount of information from a signal. Although a human operator is ultimately the best judge for optimal signal acquisition for himself, he is often not the best judge for another human observer or for a machine vision device. In addition, "man-in-the-loop" approaches prevent real-time optimization for signal acquisition. Although real time, typical AGC circuits simply adjust the gain to ensure a near-constant average signal intensity. The "minimum-mean square error" approach, limits quantization error effects, but for most signal distributions does not ensure the maximum signal information content. In fact, none of these aforementioned approaches in the prior art are optimal in the information-theoretic sense and none address the case where the signal is corrupted by noise.